First things first, I don't believe this is a Bukkit bug proper, but most likely a plugin conflict / issue. I need help narrowing down what exactly could be the cause. I'm running CraftBukkit 1.6.4 RC 2.0. My current plugins setup: MyriadAxe, StructureSaver, killStats, WorldEdit, WorldGuard, SimpleConceal, EnderChestViewer, BeardStat, Pigasus, CommandBook, Flight, AnimalProtect, Vault, PermissionsEx, ChatManager, SimpleReserve, LWC, Whitelist, dynmap, Dynmap-WorldGuard, IOTracker, IOLogger, IONotifier, MineBackup, CraftIRC, BKCommonLib, NoLagg NoLagg is primarily used for profiling and has most of it's features disabled. Now, the problem proper: for a while now, we've been suffering from slowdowns, with the server's TPS being constantly anywhere between 5.0 and 16.0. I managed to narrow it down to LWC and hoppers. Switching to a dev build of LWC got rid of that and got us back to a nice TPS close to 20.0. The current problem, however, happened a few minutes in. The server started running too fast. The server's TPS would vary wildly but would often find itself at 25.0, 30.0 and I've even seen 35.0. Sometimes, it'd dip back to 15.0 only to come back up. This is obviously not wanted and creates choppy gameplay. Disabling LWC completely still caused the server to run too fast, so that's not it. I'm ready to dive in and run some more tests, disabling plugins one by one if I have to, but I thought I'd ask here first if someone had faced this before and came up with a solution. Thank you for reading!